Overbased sulfonates

ABSTRACT

A lubricating oil additive having an alkali value above 400 is made by reacting an oxide of a metal of Group II with methanol and carbon dioxide and emulsifying with an oil soluble sulfonate in a succession of stages, the resulting carbonate dispersion being stabilized by treating with water, then dehydrating after each stage.

I United States Patent 1 1 1111 3,878,116

Rueckert Apr. 15, 1975 [54] OVERBASED SULFONATES 3,155,616 11/1964Voorhees 252/33 3,223,630 12/1965 Gragson 252/33 [751 Invenm HansRueckm, Nuys 3,262,880 7/1966 Voorhees 252/33 73 A I B 1 L A 1 3,318,8095/1967 Bray 252/33 Ssgnee (zompany OS nge 3,488,722 1/1970 Allphin252/33 3,595,790 7/1971 Norman et a1 252/33 [22] Filed: Sept. 9, 19703,658,703 4/1972 Gragson et al 252/33 (Under Rule 47) PrimaryExaminerDe1bert E. Gantz [21] Appl. No.2 70,857 Assistant Examiner-1.Vaughn 52 us. c1 252/334; 252/33 [57] ABSTRACT v 51 Int. Cl. Cl0m 3/34;C10m 3/02 A lubricating Oil additive having an alkali value above [58]Field of Search 252/334, 18, 25, 33 400 is made y reacting an Oxide of ametal of Group II with methanol and carbon dioxide and emulsifying 5References Ci with an oil so1ub1e sulfonate in a succession of stages,UNITED STATES PATENTS the resulting carbonate dispersion beingstabilized by treating with water, then dehydrating after each stage.2,881,206 4/1959 KJOHHZS et a1. 252/334 3,105,049 9/1963 Voorhees 252/338 Claims, 1 Drawing Figure PATENTEDAPR 1 5197s METf/A/VOL REC VCLEsou/Em L R YER PRE- C'ARBO/VA T/0/V 26 OIL- S ULFOA/AT E SOLUT/O/VEMULSION STAGE I Gof /2 ME T HA/VOL STRIP WATER WATER TREAT DEH YDRA TEFILTER C'OMPL EX WATER EMULS/O/V 5T4 GEE METHANOL STRIP WATER TREATFILTER v METHAIVOL SOLUTION DEHYDRA TE J EMULSION smeslzz 37 f a ME THA/VOL S T/?/ P WA TER TREA T DE H YDRA TE FILTER SOLVE/VT STRIP HIGHBASIC PRODUCT IN VE/V l/A/vs u. Run/(5m- 1 OVERBASED suLroNATps Thisinvention relates to the manufacture of oil soluble sulfonates of highreserve alkalinity and to the process of making them. More particularly,it relates to dispersions in oil of the carbonates of metals of Group 11of the Periodic System in which the carbonate particles are of colloidaldimensions, below 0.1 micron, leaving the oil transparent to visiblelight.

In recent years, it has been found very desirable to add to lubricatingoils particularly oils used in internal combustion engines, marineservice, and similar applications .where acids and corrosion areencountered basic substances which all neutralize acids as they arise inthe operation of the machine before they reach a concentrationsufficient to attack the machine parts or catalyze the formation ofsludge in the oil. Colloidal carbonates of the alkaline earth metals,particularly calcium and barium, have been found ideally suited to thepurpose, owing to their water insolubility. Because of their lowercombining weight, calcium and magnesium offer certain advantages overbarium. These carbonate dispersions are stabilized by oil solublesurface active agents such as the fatty acid soaps, the phosphonates,and especially the sulfonates of the alkaline earth metals in which thesulfonic acid portion of the molecule has a molecular weight above about400 usually 450 to 600. These sulfonates are made by sulfonation oflubricating oil fractions from petroleum and by sulfonation of alkylbenzenes having the desired molecular weight, as is well known in theart. Benzene alkylates with straight chain alkyl groups are especiallyde' sirable.

Numerous patents have been issued on processes of making these carbonatedispersions in oil. Because of the many requirements such dispersionsmust meet such as transparency, stability at elevated temperature, waterresistance, storage stability, filterability, freedom from corrosivesalts, and high ratio of excess metal above that in combination with thesurface active agent many problems have been encountered in theirmanufacture. Perhaps the most successful methods involve making acomplex between an alcohol, the oxide or hydroxide of an acid acceptingmetal and CO then dispersing the complex in a lubricating oil andremoving the alcohol and unreacted solids. Such methods are described inU.S. Pat. Nos. 3,105,049; 3,155,616; 3,170,880; and 3,170,881, and inBritish Pat. No. 789,820 published Jan. 29, 1958. The role of water inthe reaction is a much debated matter, but indications are that thepresence of more than a trace of water in the carbonation stage resultsin a coarser particle and a less desirable product.

The complex of metal oxide, alcohol, and CO can be formed in solution inthe absence of the oil and dispersant, then mixed with the oil anddispersant to form an emulsion from which the-alcohol is removed bydistillation as in U.S. Pat. No. 3,105,049, or the oil, dispersant,alcohol, and oxide can be emulsified, then carbonated. In either case,difficulty is usually encountered when the product has an alkali valueabove about 250 mg. KOl-l per gram equivalent, owing to gelling of thecomplex on removal of alcohol usually methanol. In this case, gellingand caking on the coils or other heating surfaces may take place whenthe temperature reaches about 175F. Use of a hydrocarbon solvent such asxylene, toluene, or petroleum naphtha aids in preventing gel separation.Addition of water will break the gel and reverse the phases of theemulsion, making it oil continuous, but it is dangerous to introducewater before all free methanol has been removed which usually requires atemperature of 220-260F., inasmuch as water in the presence of alcoholcauses a degradation of the dispersed carbonate to a cloudy or muddyproduct which is impossible to clarify and which usually cannot befiltered, even with large additions of filter aid such as diatomaceousearth.

One object of this invention is to produce an oil having a hightitratable alkali value above 350 and preferably above 400. Anotherobject of the invention is to produce an oil having a high metal ratio,i.e., the ratio of total metal to that combined with the dispersant,e.g., the metal sulfonate. The invention is illustrated by a drawingwhich is a flow diagram of the process.

1 have discovered that oils of high alkali value above 400, and even upto 600, can be made by conducting the process in a succession of stages,limiting the amount of metal oxide used in each stage to give not morethan an increase of about 200 milligram KOH equivalents per gram,generally about l00200, except in the first stage which can be made to250 or even 300 alkali value. In each stage, however, it has been foundessential to remove the alcohol and treat the oil with water, thendehydrate, usually at 250 to 350F. to stabilize the carbonatedispersion, before it is subjected to further treatment with oxide, COand anhydrous alcohol. Thus, when employing a lubricating oil containingabout 40 percent neutral calcium sulfonate representing 1.6 percentcalcium as metal, an initial treat with 16-18 percent calcium oxide,methanol, xylene solvent, and CO gives an oil which, after methanolstripping, water treating, and dehydration, has an alkali value of 250.When this oil is retreated with oxide, methanol, and CO using only about8-10 percent of oxide, the final oil product has an alkali value of 400,and no gel trouble is encountered. From this, it appears that thetreatment with water followed by dehydration has rendered the colloidalcarbonate inert.

. Inasmuch as the hydrocarbon diluent employed to facilitate mixing andcontact has a boiling point substantially above that of the alcohol, itcan be largely left with the oil after the initial and intermediatestages of the process, even aiding in the dehydration by azeotropingwater from the product. Removal of water from the carbonate dispersionin the intermediate stages is essential to prevent degradation tocoarsely colloidal carbonate which imparts a cloudy appearance to' theproduct, sometimes called mustard." Water appears to associate with thecarbonate and evaporates from it with difficulty, even at 300400F.Presence of the hydrocarbon solventboiling at about 380F. isadvantageous. Petroleum xylene boiling at about 2803l0F. is quitesatisfactory. Petroleum naphtha known as varnish makers and paintersnaphtha (V.M.&P.) can also be used. The amount employed is usually about2 to 3 times the volume of the oil-dispersant solution. It can berecovered from the product oil by distillation and steamstripping andrecycled in the process after separating water by settling and/orabsorption in calcium chloride, silica gel, etc.

The sulfonate employed can be made by sulfonation of solvent refinedlubricating oil, using oleum as in U.S. Pat. No. 2,689,221, or it can bemade by sulfonation of a benzene alkylate, preferably the higher boilingfraction from alkylation of benzene with an olefin or a monochlorhydrocarbon of about -13 carbon atoms having a normal or straight chainstructureQSuch an alkylate has the following characteristicsz- Gravity.API 28-32 Pour Point, F. 70 Flash, C.O.C. 420 Viscosity, cs. at 100F.35-25 Molecular Weight 400 Distillation at 10 mm.

Initial. T. 412 571 444 50% 494 907: 534

When this alkylate was blended with a neutral oil such as 150 neutral ina ratio (volume) of 45 alkylate to 55 neutral, the blend sulfonated witholeum to yield a product, after neutralization with lime, having acalcium sulfonate soap content of about 40-45 percent by weight and aneutral calcium content of 1.55 percent determined by the quarternaryammonium sulfonate method (Q.A.S.). This method is described inAnalytical Chemistry, Volume 26, Sept., 1954, pages 1,492-97; also inTechnical Bulletin, Rohm and Haas Company, Feb., 1960, Assay of HyamineProducts". The Alkali Value (or Acid Value) is determined by ASTM MethodD664-58 and is expressed in milligrams KOH equivalent per gram ofsample. Ash (sulfated) is determined by ASTM Method D874-59T. By metalratio" is meant the ratio of total calcium to Q.A.S. calcium, i.e. thatin combination with organic acid.

The following examples illustrate batchwise operations in stages,employing calcium sulfonate of about 900 molecular weight in lubricatingoil containing about 1.6 percent calcium, equivalent to about 38 to 40percent sulfonate.

EXAMPLE 1 222 cc, methanol was placed in a turbine mixer with 255 cc.xylene solvent and grams calcium oxide. CO was passed in until thetemperature rose 20F. Then, 100 grams of calcium sulfonate-oil wasadded, diluted with 120 cc. xylene solvent. CO was continued until adrop in temperature showed the reaction was ended. Methanol was thenevaporated by heating to a temperature of 260F. without encountering gelformation. The oil was then cooled to 200F. and treated with 50 cc.water, then dried by heating to 280 and filtered. The clear solution wasstripped to 400F. and the resulting oil tested for alkali value. Withphenolphthalein indicator, it tested 18, and with methyl orange, 240.

To 100 grams of the above oil was added 100 cc. xylene for dilution.This solution was added to a mixture of 222 cc. methanol, 255 cc.xylene, and 20 grams calcium oxide which had been carbonated to atemperature rise of 20F. The mixture of oil and metal oxide complex wasthen further carbonated until the temperature began to fall, indicatingcompletion of the reaction. Methanol was then distilled off to atemperature of 230F. The oil was then again treated with 50 cc. waterand dehydrated to 280F. After filtering and stripping solvent, theproduct oil titrated 425 basic.

EXAMPLE 2 In a three stage operation, 200 cc. anhydrous methanol and 300cc. xylene were mixed in a turbine mixer with 18.6 gm. CaO. Afterinitial carbonation with CO there was added grams calcium sulfonate-oilsoluble type, having 1.58 percent combined calcium content. Carbonationgave a rise in temperature from 77 to F.

Methanol removal and water treating followed as in Example 1. Thesolvent-free oil tested 235 alkali value.

100 grams of this oil were treated as just described, using 16 gramscalcium oxide this time. No gelling occurred on removal of methanol bydistillation. The oil product, after water treatment and drying, tested405 alkali value.

In a third stage, 100 grams of this oil were again treated as above,using 11 grams of calcium oxide in preparing the methanol-CO complex.The temperature rose during carbonation from.80 to 1 12F. No gelappeared during the removal of methanol. After water treating,dehydration, filtering, and stripping, the clear red brown oil producttested 510 alkali value. It was a viscous oil, but flowed readily atroom temperature.

EXAMPLE 3 This example gives the results of four successive stages,beginning with a neutral sulfonate-lubricating oil of 1.6 percentcalcium content.

STAGE I In the first stage, 27 grams of calcium oxide were partiallycomplexed with 200 cc. methanol and 350 cc. xylene solvent, passing COinto the mixture. To the mixture were then added 150 grams ofoil-sulfonate and carbonation was completed within 30 minutes. Methanolwas then stripped off to a temperature of 260F. The product was thentreated with 75 cc. of water, dehydrated, filtered, and stripped ofsolvent at 350F. Alkali value was 235.

STAGE II The above operation was repeated with 150 grams of the 235 A.V.oil. No gelling occurred on removal of methanol and the product tested420 alkali value.

STAGE III The above operation was again repeated with 150 grams of the420 A.V. oil but using only 15 grams of calcium oxide. No gelling wasencountered. The product was a free flowing red-brown oil of 505 alkalivalue.

STAGE IV In this operation, 19 grams of calcium oxide were complexedwith methanol and CO as before and grams of the 505 A.V. oil were used.To the mixture was added 200 cc. more xylene solvent to maintainfluidity. Methanol was removed from the fully carbonated reactionmixture by heating to 260F. without trouble from gel formation. Aftertreating with 100 cc. water, dehydrating, filtering, and stripping to400F., the heavy oil product tested 600 alkali value. Although quiteviscous, it flowed readily at ambient temperature.

EXAMPLE 4 A 2 stage pilot plant batch operation was conducted asfollows:

10 gallons of xylene solvent and 10 gallons of methanol 0.35 percentwater content were mixed with 9.5 pounds CaO. CO was passed in at 66F.When the temperature reached 88", 53 pounds of calcium sulfonate-oilcontaining 1.55 percent calcium were added,

20 minutes at 155F. 35 minutes at 165F. 55 minutes at 285F. 65 minutesat 292F.

5 gallons over 5 gallons over 5 gallons over 4 gallons over Total lbgallons Considerable amounts of xylene solvent distilled over with themethanol in later fractions. The oil was treated with 1,300 cc. water at180F. Seven gallons of xylene solvent were added as make-up. Water wasdistilled off to 290F., taking over 5 gallons xylene. The oil-solventsolution was filtered with standard diatomaceous earth, recovering l l 1pounds of solution, clear. A test showed 54 percent solvent-free oilanalyzing 245 alkali value with methyl orange indicator.

1n the second stage, 9 pounds of calcium oxide were used in the samemixture as above and carbonated for 19 minutes while the temperaturerose from 70 to 90F. The oil solution (111 pounds) was added and COcontinued for a total of 58 minutes, terminating the reaction at 135F.Seventeen gallons of methanolsolvent were distilled off to 290F. and 7gallons of solvent were added to the oil as make-up. 1,300 cc. water wasadded at l90F., thoroughly mixed and dehydrated to 290F., taking over9.5 gallons xylene with the excess water. The product oil-solventsolution filtered rapidly with diatomaceous earth filter aid giving aclear solution containing 59 percent oil free of solvent. Analysisshowed a combined calcium (Q.A.S.) of 1.09 percent and alkali value of400. When stripped with steam at 300F., the final product weighed 60.5pounds and had the following analysis:

Alkali Value 395 Color Bright. clear red Q.A.S. 1.07%

Sediment 0.02%

Flash "325F.

Water 0.35'71 Referring to the drawing, a solution of metal sulfonate inoil, usually of 30 to 60 percent concentration Q.A.S. calcium of about1.25 to 2 percent is prepared in 10. It is convenient to have thissulfonate solution diluted with hydrocarbon solvent in a ratio of about1:1 by volume. Toluene, xylene, petroleum naphtha, etc. can be used forthe purpose, a petroleum xylene boiling in the range of about 280-310F.being quite satisfactory. From 10, the solution flows to the firstemulsion stage 11, where it is mixed with the desired amount ofmethanol-metal oxide-CO complex from precarbonator 12, introduced byline 13. This reagent complex is prepared by mixing, with goodagitation, metal oxide,'methanol, and C0 The methanol is substantiallyanhydrous but may contain from 0.1 to 0.5 percent water, which, in somecases, accelerates the formation of the complex. More water than thismust be avoided as it has an adverse effect on the final metal carbonatedispersion. When recycling methanol in the process, it is alsoconvenient to have solvent present in precarbonator 12, which, in thecase of xy' lene, may amount to to 25 percent by volume of the mixture.

I prefer to employcalcium oxide in the process, usually made by a lightroast at 1,800-2,000F. and ground to about 250-300 mesh or finer. Bariumoxide can also be used, as can MgO when in an active state. In the caseof magnesium, the metal can be dissolved in methanol to give themethylate which can be added in methanol solution. Carbonation is rapid,the reaction being completed within about 5 to 10 minutes. Thecarbonation can be carried to completion or stopped part way, forexample, when the temperature of carbonator 12 has risen about 20F. Theratio of lime to methanol is usually about 1:10 to 1:15 by weight.

The rate of transfer of carbonated complex to reactor 11 can becontrolled by automatic flow controllers in a continuous plantoperation. I prefer to control the rate to give an alkali value in Stage1 of about 200-300, while the increase is less in later stages. Themixture in 11 is suitably 1 volume of lube oil-sulfonate, 2 volumes ofmethanol, and 3 volumes of hydrocarbon diluent. Additional CO isintroduced by line 14 in case the complex from 12 is incompletelycarbonated. The temperature of the emulsion may range from 1 10 to 150F.The mixture next flows to methanol stripper 15 where the methanol isremoved by heat to 260 and vapors of methanol are withdrawn by line 16leading to recycle line 17, condensation not shown. Some solvent vaporscome over with the methanol, especially toward the end of the strippingoperation when the temperature reaches about 260 to 280F. and recycleswith the methanol without interfering with the reaction.

From stripper 15, the oil with solvent passes next to water treater 18where it is mixed with sufficient water to convert it to a water-in-oiltype emulsion. I believe the water serves to hydrate the carbonate,rendering the colloidal particles or micelles stable and resistant tocoagulation. The dispersion now has lost its gelling tendency andbehaves like a true lubricating oil. The amount of water required isabout 1 to 4 mols per mol of metal oxide present. It should be mixed ata temperature below the boiling point, e.g., 200F., then heated todehydrate. The resulting emulsion passes to dehydrator 19 where it isheated to drive out the water, for example, to 260-290F. The water andsolvent vapors pass by line 20 to line 21, thence to water separator 22where water settles out and is drawn off at 23, condensation not shown.Some methanol released from the complex in 18 will be found in the waterat 23 and can be recovered if desired. Solvent passes to dryer 24 whereany remaining dissolved or entrained water is removed, for example, withfused CaCl flakes, before returning by line 25 to carbonator 12. Ifdesired, solvent can be passed into sulfonate in 10 by line 26.

The colloidal carbonate dispersion in 19 may be clarified in filter 27before passing to emulsion stage 11 in 28. However, if the metal oxideemployed in the process is sufficiently pure, for example, 98 percent orbetter, filtration can be omitted. The sulfonate-oil solution in 19should contain an equal volume of hydrocarbon solvent, e.g., xylene. Ifneeded, more solvent can be added at this stage by line not shown.

Into mixer'28 is introduced a stream of methanollime complex from 12 bylines 29 and 30 at a rate sufficient to increase the base number of theoil by about to 200 mg. KOH per gram equivalent. in my continuousoperation, this is conveniently accomplished by means of a flowcontroller on the feed line 30. Additional CO is introduced by line 31as needed to complete the carbonation of metal oxide not fullycarbonated in 12. Methanol is next distilled off in 32, the vaporspassing into line 17 and condensed by condenser not shown, in a mannerwell known to the art. The temperature of stripper 32 is about the sameas in l5.

After cooling to about 200F. or below, the oil is next treated withwater in 33 as in 18, sufficient water being added to hydrate the metalcarbonate introduced by line 30. The oil is next dehydrated in 34 byheating to the boiling temperature of the solvent, about 280F. in caseof xylene and about 240F. in case of toluene. Optionally, theoil-solvent solution is then filtered in 35 and conductedto emulsionstage 36 wherein it is mixed with a further amount of the methanol-limecomplex from 12 led by lines 29 and 37. The amount of metal complexshould be sufficient to increase the base number of the oil by about100-150 mg. KOl-lper gram equivalent. Carbon dioxide enters 36 by line38 as required to complete the carbonation.

The emulsion from 36 then is stripped of methanol in 39, the methanolwith some solvent passing to recycle line 17. The oil is next watertreated again in 40, liberating combined methanol from the metal oxidecomplex and hydrating the carbonate. Excess water and a part of thehydrocarbon solvent is then removed in dehydrator 41, the vapors beingcondensed by condenser, not shown, and led by line 42 into recycle line21. The solution is then filtered in 43 and stripped free of solvent byheating in still 44 where steam can be used to complete removal ofsolvent from the oil. Finished product oil flows from stage 44 by line45 and may be again filtered hot if desired. By this three stageprocess, I have been able to make oils having a base number of 600. Forbase numbers of 400 to 500, I can operate with only two stages, removingthe oil after dehydration stage 34 and filtering and stripping it in 43and 44. Filtration of the oil in 43 is greatly facilitated by filtrationbetween stages, thus reducing the amount of troublesome solids to beremoved in the final clarification, particularly in cases where themetal oxide employed contains more than 23 percent of unreactivematerial such as silica, iron oxide, etc.

Having thus described my process, what I claim is: 1. The process ofmaking a lubricating oil additive of high alkali value wherein anoil-soluble sulfonate of a metal of Group ll is mixed in a first stagewith a complex formed from the oxide of said metal with anhydrousmethanol and carbon dioxide, in the presence of a hydrocarbon solventboiling above methanol, the amount of metal in said complex beingsufficient to impart to said oil and alkali value of at least 250,distilling methanol from the mixture at a temperature of at least 220F.,treating the methanol-free mixture with water in an amount equal toabout 1 to 4 mols per mol of oxide present, thereby converting saidcomplex to carbonate, inert to gelling, dehydrating the mixture byheating to at least 250F., cooling the dehydrated oil and colloidalinert carbonate and mixing it in a second stage with sufficient metaloxide-methanol-CO complex to impart to the oil an alkali value of atleast 400, stripping methanol from said complex to at least 220F.,treating with water in proportion of about 1 to 4 mols per mol of metaloxide added in said secondstage and thereafter dehydrating and filteringthe product oil.

2. The additive of claim 1 wherein said Group II metal is calcium.

3. The additive of claim 1 wherein said Group '11 metal is magnesium.

4. The additive of claim 1 wherein the said Group II metal is barium.

5. The method of making an overbased lubricating oil additive of highalkali value which comprises, in a first stage, emulsifying alubricating oil solution of an oil soluble sulfonate with the oxide of ametal of Group II of the Periodic System, anhydrous methanol andhydrocarbon solvent while introducing carbon dioxide sufficient toconvert said oxide to carbonate being sufficient to impart to said oilan alkali value of about 250300, removing the methanol by distillationat about 200-260F. and then hydrating the carbonate by treating withwater in an amount equal to about 1 to 4 mols per mol of oxide present,thus rendering the carbonate inert, dehydrating the resulting dispersionto remove excess water, then repeating the treatment with oxide,methanol and water in a succession of stages until the alkali value ofthe oil has been increased to at least 400 mg. KOH per gram equivalent.

6. The method of claim 5 wherein the amount of oxide employed in thesaid first stage is sufficient to produce an oil with an alkali value ofabout 250 to 300 while, in later stages, the oxide is controlled to givean increase in alkali value of to 200 in each stage.

7. The method of claim 5 wherein the hydrocarbon solvent employed has aboiling point substantially above that of water and solvent is allowedto remain with the oil after removal of methanol, water treating anddehydration between stages.

8. The overbased lubricating oil additive prepared by the process ofclaim 5 wherein said additive has a base number of about 500 to 600milligrams of KOH per gram equivalent.

1. THE PROCESS OF MAKING A LUBRICATING OIL ADDITIVE OF HIGH ALKALI VALUEWHEREIN AN OIL-SOLUBLE SULFONATE OF A METAL OF GROUP II IS MIXED IN AFIRST STAGE WITH A COMPLEX FORMED FROM THE OXIDE OF SAID METAL WITHANHYDROUS METHANOL AND CARBON DIOXIDE, IN THE PRESENCE OF A HYDROCARBONSOLVENT BOILING ABOVE METHANOL, THE AMOUNT OF METAL IN SAID COMPLEXBEING SUFFICIENT TO IMPART TO SAID OIL AND ALKALI VALUE OF AT LEAST 250DISTILLING METHANOL FROM THE MIXTURE AT A TEMPERATURE OF AT LEAST220*F., TREATING THE METHANOL-FREE MIXTURE WITH WATER IN AN AMOUNT EQUALTO ABOUT 1 TO 4 MOLS PER MOL OF OXIDE PRESENT, THEREBY CONVERTING SAIDCOMPLEX TO CARBONATE, INERT TO GELLING, DEHYDRATING THE MIXTURE BYHEATING TO AT LEAST 250*F., COOLING THE DEHYDRATED OIL AND COLLOIDALINERT CARBONATE AND MIXING IT IN A SECOND STAGE WITH SUFFICIENT METALOXIDE-METHANOL-CO2 COMPLEX TO IMPART TO THE OIL AN ALKALI VALUE OF ATLEAST 400, STRIPPING METHANOL FROM SAID COMPLEX TO AT LEAST 220*F.,TREATING WITH WATER IN PROPORTION OF ABOUT 1 TO 4 MOLS PER MOL OF METALOXIDE ADDED IN SAID SECOND STAGE AND THEREAFTER DEHYDRATING ANDFILTERING THE PRODUCT OIL.
 2. The additive of claim 1 wherein said GroupII metal is calcium.
 3. The additive of claim 1 wherein said Group IImetal is magnesium.
 4. The additive of claim 1 wherein the said Group IImetal is barium.
 5. The method of making an overbased lubricating oiladditive of high alkali value which comprises, in a first stage,emulsifying a lubricating oil solution of an oil soluble sulfonate withthe oxide of a metal of Group II of the Periodic System, anhydrousmethanol and hydrocarbon solvent while introducing carbon dioxidesufficient to convert said oxide to carbonate being sufficient to impartto said oil an alkali value of about 250-300, removing the methanol bydistillation at about 200*-260*F. and then hydrating the carbonate bytreating with water in an amount equal to about 1 to 4 mols per mol ofoxide present, thus rendering the carbonate inert, dehydrating theresulting dispersion to remove excess water, then repeating thetreatment with oxide, methanol and water in a succession of stages untilthe alkali value of the oil has been increased to at least 400 mg. KOHper gram equivalent.
 6. The method of claim 5 wherein the amount ofoxide employed in the said first stage is sufficient to produce an oilwith an alkali value of about 250 to 300 while, in later stages, theoxide is controlled to give an increase in alkali value of 100 to 200 ineach stage.
 7. The method of claim 5 wherein the hydrocarbon solventemployed has a boiling point substantially above that of water andsolvent is allowed to remain with the oil after removal of methanol,water treating and dehydration between stages.
 8. The overbasedlubricating oil additive prepared by the process of claim 5 wherein saidadditive has a base number of about 500 to 600 milligrams of KOH pergram equivalent.